VIRIDIANS STREPTOCOCCI Flashcards
Are oropharyngeal commensals:
viridans streptococci
Normal microbiota of the URT, female genital tract and GIT:
viridans streptococci
Viridans streptococci are also known as:
alpha-prime streptococci
Causes three main types of infection:
- dental infections
- endocarditis
- abscesses
Most common cause subacute bacterial endocarditis (SBE):
viridans streptococci
Virulence factors:
“CACE”
capsule
adhesins
cytolysin
extracellular dextran
Enhance attachment to host cell surfaces, such as cardiac endothelial cells or tooth surfaces in the case of dental carriers:
extracellular complex polysaccharide
Laboratory test:
bile insoluble
optochin (R)
no growth in 6.5% NaCl
LAP (+)
PYR (-)
5 Groups of Viridans:
“BAMMS”
1. S. bovis group
2. S. anginosus group
3. S. mitis group
4. S. mutans group
5. S. salivarius group
S. mitis group:
“I PaGoMiCr PO(z)”
S. infantis
S. parasanguis
S. gordonii
S. mitis
S. cristatus
S. peroris
S. oralis
S. mutans group:
“SoMu”
S. sobrinus
S. mutans
S. salivarius group:
“SaVeT”
S. salivarius
S. vestibularis
S. thermophilus
S. bovis group:
“I GAE”
S. infantarius
S. gallolyticus
S. alactolyticus
S. equinus
S. anginosus group:
“CAI”
S. constellatus
S. anginosus
S. intermedius
Laboratory tests:
- growth in bile esculin medium
- 6.5% NaCl (nutrient broth base) test
- PYR test
- Penicillin test
Esculin hydrolysis test for the cleavage of a glycoside:
growth in bile esculin medium
Reagent of bile esculin:
esculin + 1-4% bile salt
Bile esculin test (+) result:
black color complex in the agar within 48 hours
6.5% NaCl test (-) result:
no growth
PYR test result:
negative
Penicillin test result:
susceptible
Most commonly isolated viridans:
S. mutans group
Viridans that possesses the group D antigen:
S. bovis and enterococci
Often isolated in blood cultures of individuals with GI carcinoma:
Bovis group (S.equinus)
Lancefield antigens of anginosus:
group A, C, F, G, or N
Colonies are surrounded by a very small zone of no hemolysis and then a wider zone of B-hemolysis:
alpha-prime hemolysis/wide zone hemolysis
